Fluids based on fluorocarbon compounds are widely used in vapor-compression heat-transfer systems, especially air-conditioning, heat-pump, refrigeration or freezing devices. The common feature of these devices is that they are based on a thermodynamic cycle comprising vaporization of the fluid at low pressure (in which the fluid absorbs heat); compression of the vaporized fluid up to a high pressure; condensation of the vaporized fluid to liquid at high pressure (in which the fluid expels heat); and depressurization of the fluid to complete the cycle.
The choice of a heat-transfer fluid (which may be a pure compound or a mixture of compounds) is dictated firstly by the thermodynamic properties of the fluid, and secondly by additional constraints. Thus, a particularly important criterion is that of the environmental impact of the fluid under consideration. In particular, chlorinated compounds (chlorofluorocarbons and hydrochlorofluorocarbons) have the drawback of damaging the ozone layer. Non-chlorinated compounds are therefore now generally preferred, such as hydrofluorocarbons, fluoro ethers and fluoro olefins.
It is, however, necessary to develop other heat-transfer fluids which have a global warming potential (GWP) less than that of the heat-transfer fluids currently used, and which have equivalent or improved performance qualities.
The use of ammonia as a heat-transfer fluid is known. However, a certain number of problems are associated with this compound: a very high compressor outlet temperature relative to hydrofluorocarbons; an absence of oil return and the obligation to install an oil separator; a total permitted charge that is occasionally limited on account of the toxicity of the product.
Document US 2008/0 069 177 describes a large number of mixtures of heat-transfer compounds, and especially mixtures comprising 3,3,3-trifluoropropene (HFO-1243zf) and also other mixtures comprising ammonia. The latter mixtures are, more precisely: a 1,2,3,3,3-pentafluoropropene (HFO-1225ye)/ammonia binary composition; two difluoromethane (HFC-32)/ammonia/HFO-1225ye and HFO-1225ye/pentafluoroethane (HFC-125)/ammonia ternary compositions; and three HFC-32/ammonia/HFO-1225ye/CF31, HFC-32/ammonia/2,3,3,3-tetrafluoropropene (HFO-1234yf)/CF3I and HFC-1225ye/HFC-32/HFC-125/ammonia quaternary compositions.
Document WO 2008/033 570 contains teaching similar to that of document US 2008/0 069 177.
However, there is still a need to develop other heat-transfer fluids which have a relatively low GWP, and which are capable of replacing the usual heat-transfer fluids.
In particular, it is desirable to develop other low-GWP heat-transfer fluids which are quasi-azeotropic or even azeotropic and/or which have good energy performance qualities relative to the usual heat-transfer fluids (such as R404A or R410A).